The cost of material handling is a significant portion of the cost of certain items, such as items of large bulk and/or of relatively heavy weight. Examples of such items are building materials, i.e., lumber, concrete blocks, pipe, shingles, steel beams, etc.
Such material handling includes shipping the items from the manufacturer through the distribution channel to the retailer and from the retailer to the job site at which the materials will be employed. The handling of the materials from the manufacturer through the distribution channels is usually accomplished efficiently and at minimal cost, due to the large quantities of goods being handled. However, the handling of the material from the retailer to the job site usually is not as efficient and thus greatly, and unnecessarily, increases the cost of such goods.
That is, once the items have been purchased at a retail outlet, they must be transported to the job site. Much effort and cost may be expended in delivering these items to the job site.
For purposes of illustration, the handling and transport of building materials is addressed below. While the handling of building materials is specifically addressed, the devices according to this invention can be employed to handle many other objects. Building materials are discussed merely as an example of the types of goods which can be handled, and not as a limitation on the scope of the invention.
Building materials are usually delivered from a retail establishment or warehouse to a job site via a flat bed truck, delivery van or other cargo carrying vehicle. The building materials are usually loaded onto the cargo vehicle by a forklift at the retail establishment or warehouse. Commonly, the smaller building materials, such as concrete blocks, are stacked on wood pallets of uniform size. These wood pallets include spaced layers of boards. The fork of the forklift is inserted into the space between the layers and is operated to lift the pallet and load of concrete blocks onto the cargo vehicle. Drums of materials, lumber, pipe, shingles and other heavy materials are usually handled in the same manner. Since most business establishments that sell such building materials have a forklift available, the loading of the vehicle is not usually much of a problem or expense.
The difficulties in delivering items such as building materials usually arise at the job site to which such materials are being delivered.
If a forklift is available at the job site, then the materials can be unloaded in the same manner that they were loaded. However, frequently, a forklift is not available at the job site since such materials are usually being delivered to a construction site at which construction has not yet begun or is just getting underway. Moreover, the job site may be a single new house, a few new houses or an addition to an existing house. The small size of these jobs does not merit the expense of having a forklift on the job site.
While an apparent solution would be to haul a forklift on the vehicle with the load, this is not a viable solution because the retail establishment or warehouse does not usually have spare forklifts to send out with every truck, the retailer does not want to be liable for damage or injuries incurred using their forklift under these circumstances, and the forklift would take up valuable payload space and weight on the vehicle cargo bed.
Therefore, often a forklift is not available at the job site to unload building materials from a cargo vehicle. Under these conditions, the most frequently used method of unloading the vehicle is hand labor. However, this is dangerous, costly and time consuming work. It is dangerous in that the building materials include heavy items which may cause injury to the workers if mishandled or if a worker has an accident while handling the items (such as slipping in mud).
Moreover, this work is costly since a great deal of time is involved in removing heavy and/or bulky items from a motor vehicle by manual labor. This problem is compounded because the vehicles are usually loaded by the forklift at the retail establishment.
Further the unloading process usually must involve at least two workers due to the weight and/or bulk of some of the building materials.
This requires that, at the least, the driver have a helper to unload the vehicle. In circumstances when the materials are being delivered to a new job site, a helper may not be readily at hand. This may result in further delay as a helper is located and arrives at the job site, or to avoid this delay, a helper must travel with the driver.
If the helper travels with the vehicle, this greatly increases the labor costs for delivering the goods. If the helper is to be supplied at the job site, this may make the delivery schedule critical to assure that the vehicle arrives at the job site when the worker is present and available to help unload. Moreover, the use of a worker at the construction site slows down the construction work as the worker's time is spent unloading vehicles and not doing actual construction tasks.
In view of these problems, certain types of mechanisms have been developed to help unload vehicles with heavy or bulky payloads at job sites.
One type of such devices is the hydraulic lift tailgate which is employed with a closed van. This is a tailgate which is normally perpendicular to the cargo bed of the closed van, but which may be oriented parallel to the bed of the closed van for lifting and lowering cargo. The tailgate can be hydraulically raised and lowered with a load on it to move the load from the level of the cargo bed of the closed van to the ground and vice versa. However, while this is an advance in the art, hydraulic lift tailgates still have many disadvantages.
First, the load must still be transferred from all locations on the cargo bed of the closed van to the hydraulic lift tailgate during the unloading process. Then once the load has been lowered to the ground, manual labor must again be employed to move the cargo from the tailgate to the ground. Thus, a substantial amount of manual labor is still involved. The only manual task which the hydraulic lift tailgate renders unnecessary is the lowering of the payload down from the vehicle bed to the ground, and vice versa.
Another mechanism which has been developed to unload such vehicles are built-in cranes. These cranes are built as part of the truck, either between the truck cab and truck bed or on the truck bed. These cranes have the disadvantage of being relatively expensive and undependable. Moreover, the cranes take up valuable payload space. That is, on vehicles having these built-in cranes, less space is available to carry the cargo, which in turn, means less profit per trip. Further, the cranes are heavy. This may permit the truck to carry less cargo weight since the crane takes up some of its maximum payload capacity.
Therefore, it is clear that neither the hydraulic lift tailgate or the equipping of cargo vehicles with built-in cranes is an adequate or optimum solution to the problem of unloading heavy and/or bulky cargo at a job site.
In view of this, many specialty devices have been developed which may be attached to cargo carrying vehicles for loading and unloading cargo. Examples of these devices are disclosed in U.S. Pat. No. 2,702,678 issued to Flock, Jr. on Feb. 22, 1955; U.S. Pat. No. 2,732,087 issued to Pratt on Jan. 24, 1956; U.S. Pat. No. 2,993,607 issued to Tapper on July 25, 1961; U.S. Pat. No. 3,504,810 issued to Walda on Apr. 7, 1970; U.S. Pat. No. 3,715,046 issued to Marklund on Feb. 6, 1973; U.S. Pat. No. 3,945,516 issued to Peck et al on Mar. 23, 1976; U.S. Pat. No. 4,249,842 issued to Johnson on Feb. 10, 1981 and U.S. Pat. No. 4,498,829 issued to Spikes on Feb. 12, 1985.
Moreover, specialty forklift devices have been developed to address this problem. Such forklift devices are disclosed in U.S. Pat. No. 2,962,180 issued to Vossenberg on Nov. 29, 1960; U.S. Pat. No. 3,563,341 issued to Burtman on Feb. 16, 1971; U.S. Pat. No. 4,365,921 issued to Brouwer et al on Dec. 28, 1982; U.S. Pat. No. 4,415,302 issued to Brouwer et al on Nov. 15, 1983 and U.S. Pat. No. 4,498,837 issued to Kooi et al on Feb. 12, 1985.
However, all of these devices are limited in their use. The forklift devices must still be provided at each and every job site. The devices which are attachable to a vehicle, disclosed in the first listed patents, all have the limitation that they cannot remove loads of any size from all locations of the truck bed without manual labor, which is the same problem with the hydraulic lift tailgate.
Therefore, it is apparent that there still exists a need in the art for a load-carrying attachment for motor vehicles which can remove loads of all sizes from all locations on the truck bed. This invention addresses this need in the art, as well as other needs which are apparent to those skilled in the art once given this disclosure.